An experiment is set up to test whether a particular insect prefer a dark or a bright environment. A chamber with a gradient in light intensity from one end (dark) to the other (bright) has been made. The experimental hypothesis is:“There will be a large difference between the number of insect in a dark side and the number in a bright side of the chamber.”Which one could be the three confounding variables?

A - Varying humidity across the chamber B - The orientation of the chamber C - The age of the insects D - The non-reflective material from which the chamber is made E - The type of light source used F - Varying temperature across the chamber

I was thinking A, E and F but there is something wrong .. and also did B,E and F still wrongAny help would be appreciated. Thanks

Er...you left out the time of day or year. The question is, one would expect insects to have some sort of biological clock going, by which they like to be in light or darkness for N hours. Their response should vary considerably according to the length of their exposure to artificial light.

They could all be potentially confounding, if the insects sense and respond to -A - HumidityB - GeomagnetismC - Different stimuli at different agesD - Polarization of light interacting with the materialsE - Frequencies of lightF - Temperature